This invention relates to multiple pane insulating windows and, more particularly, relates to a cornerpiece for joining adjacent spacer bars used to separate the panes of a multiple pane insulating window.
It is well-known in the art to provide a window having more than one pane of glass, the panes being separated by an airspace. Such windows are known as insulating windows by virtue of the fact that the air trapped within the space between the panes of glass serves as an insulator to reduce heat flow through the window panes. It is common in such windows to separate the panes of glass by a frame comprised of sections of tubing joined together at adjacent ends and lying between the panes and extending around the perimeter of the window panes. These tubes are commonly made of aluminum. In order to prevent the window panes from fogging, it is necessary to keep the air which is trapped between the window panes as dry as possible. A desiccant, for example, silica gel, is oftentimes placed into the spacer tubes to absorb moisture from the air trapped within the space between the window panes. In order to prevent the desiccant from settling to the bottom of the tubular spacer frame when the window is in an upright position, it is necessary to block the ends of the sections of spacer bar to keep the desiccant within the separate sections of the spacer.
Prior attempts at providing a cornerpiece which both joins the spacer tubes and blocks the ends of the tubes are shown in U.S. Pat. Nos. 3,553,913 and 3,280,523. Most prior art spacers have comprised solid blocks of material inserted into the ends of the bars. Many of these blocks have been composed of zinc or zinc alloy. It is undesirable to use such solid pieces of zinc to block the ends of the tubes for at least two reasons; one is the fact that by using solid blocks of zinc a great deal of material is used, resulting in a higher production cost and an increased weight of the assembled unit; and secondly, the electrolytic reaction between the zinc plug and the aluminum tubing causes a rapid deterioration of the zinc plug and the formation of the zinc oxide which weakens the strength of the corner joint. Also the white, powdery zinc oxide finds its way into the space between the window panes causing an unsightly deposit on the interior of the window. It is also possible to make the solid end plugs of the prior art out of plastic or rubber. However, plastic and rubber both deteriorate with time, particularly since they will be contacting the desiccant which has a high moisture content due to absorption of moisture from the air trapped within the space between the window panes. This moisture can cause deterioration of the rubber. Also, the joint formed by the rubber or plastic end pieces is not as strong as a metal corner joint would be.
It is therefore an object of this invention to provide a cornerpiece for joining the adjacent ends of tubular spacer bars used to separate the panes of glass in a multiple pane window.
It is a further object of this invention to provide a cornerpiece which is lightweight and uses a minimum of material.
It is a still further object of this invention to provide a cornerpiece which is constructed of the same material which the spacer bars are made of, preferably aluminum.
It is a further object of this invention to provide a unitary cornerpiece formed of aluminum sheet and formed so as to block the ends of the spacer tubes to prevent leakage of desiccant from within the spacer tubes.